Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/002—Mixed oxides other than spinels, e.g. perovskite
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J23/24—Chromium, molybdenum or tungsten
  • B01J23/28—Molybdenum
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
  • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
  • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
  • B01J23/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
  • B01J23/85—Chromium, molybdenum or tungsten
  • B01J23/88—Molybdenum
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C201/00—Preparation of esters of nitric or nitrous acid or of compounds containing nitro or nitroso groups bound to a carbon skeleton
  • C07C201/06—Preparation of nitro compounds
  • C07C201/08—Preparation of nitro compounds by substitution of hydrogen atoms by nitro groups
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2523/00—Constitutive chemical elements of heterogeneous catalysts

Definitions

• the present invention relates to a process for vapor phase nitration of benzene using nitric acid over molybdenum silica catalyst.
• the invention particularly relates to a process for the preparation of mono-nitrobenzene wherein the nitration of benzene is carried out in vapor phase using molybdenum silica catalyst and nitric acid.
• nitrobenzene has been prepared in high yield in a continuous process without any waste byproduct formation making it an environment friendly process.
• nitrobenzene Major part of nitrobenzene (95% or more) produced is converted to aniline, which has hundreds of downstream products.
• Nitrobenzene also is used as a processing solvent in specific chemical reactions. Conventionally nitrobenzene is produced by liquid phase reactions employing mixed acids. A sulfuric acid/nitric acid mixture is the most commonly used nitrating agent. Generation of large amount dilute sulfuric acid, organic wastes and products of their neutralization makes the benzene nitration one of the most environmentally harmful processes.
• Vapor-phase nitration of benzene to nitrobenzene over zeolite is expected to be a clean process without sulfuric acid waste.
• a number of heterogeneous catalysts have been proposed for this process.
• U.S. Pat. No. 2,431,585 describes vapor phase nitration of aromatic hydrocarbons at temperature from 130° C. to 430° C., using metal phosphates of calcium, iron, magnesium and solid supported phosphoric acid catalysts.
• U.S. Pat. No. 5,030,776 describes a process for nitrating benzene using nitric acid as a nitrating agent under continuous or intermittent feeding of sulfuric acid as a catalyst on a solid carrier. Vapor phase nitration of benzene has been claimed in U.S. Pat. No. 5,004,846 wherein nitric acid is used as a nitrating agent and a composite oxide or acidic sheet clay mineral ion exchanged with polyvalent metal as a catalyst.
• PCT International Patent Application No. WO 96/36587 describes a solvent free process for the nitration of aromatic compounds in which the aromatic compound is reacted with nitric acid in presence of an acid anhydride wherein the process is catalyzed by an aluminosilicate catalyst.
• Nitric acid and acid anhydride react with each other in-situ to form acyl nitrate and this acts as a nitrating agent for aromatic compounds.
• benzene, naphthalene, anthracene, toluene etc. are nitrated to mononitrated compounds.
• a mixture of ortho-, meta-, and para-nitrotoluenes is obtained which is then distilled at a pressure of 30 mmHg and a temperature of 30° C. to remove acetic acid as a byproduct.
• the main object of the present invention is to provide a process for vapor phase nitration of benzene using nitric acid and over molybdenum silica catalyst.
• Another object of the present invention is use of ethyl silicate-40 as silica source for the preparation of high surface area MoO 3 /SiO 2 catalyst.
• the present invention provides a process for the vapor phase nitration of benzene, which comprises nitrating benzene with nitric acid over a molybdenum silica catalyst and separating the desired product.
• benzene is nitrated with nitric acid in the presence of a carrier gas comprising an inert gas.
• the nitration is carried out in a conventional downflow reactor containing inert ceramic packing as preheater.
• the catalyst is used without a promoter.
• the catalyst is used with a promoter comprising 0.5-2% of a transition metal oxide.
• the nitration is carried out at a temperature in the range of 100-250° C. and at a reactant weight hourly space velocity (WHSV) in the range of 0.1 to 1.0.
• WHSV weight hourly space velocity
• resulting product is condensed and then washed with alkali to obtain the desired product.
• the catalyst used is in the form of a pellet.
• the mesh size of granulated molybdenum silica catalyst used is in the range of ⁇ 10 to +20 mesh size.
• the catalyst used is MoO 3 :(1 ⁇ x) SiO 2 where x is 0.2.
• the MoO 3 /SiO 2 catalyst used is in amorphous or crystalline form.
• the molybdenum silica catalyst is in amorphous form.
• the molybdenum silica catalyst is used along with a promoter comprising 1-2% transition metal oxides selected from the group consisting of Fe 2 O 3 , CuO, NiO and Co 3 O 4 .
• the promoter is Fe 2 O 3 .
• the nitric acid used is 10 to 70% nitric acid.
• the molar ratio of nitric acid to benzene is in the range of 4:1 to 1:4.
• the ratio of nitric acid to benzene is 1:2.
• the nitration is carried out at a temperature in the range of 120-200° C.
• the inert gas used is selected from the group consisting of nitrogen, helium and argon.
• the reactant weight hourly space velocity used is in the range of 0.15 to 0.5.
• WHSV weight hourly space velocity
• the present invention provides a process for the vapor phase nitration of benzene, which comprises nitrating benzene with nitric acid over a molybdenum silica catalyst and separating the desired product.
• WHSV weight hourly space velocity
• the catalyst is used in the form of a pellet.
• the mesh size of granulated molybdenum silica catalyst is in the range of ⁇ 10 to +20 mesh size.
• the catalyst used is MoO 3 :(1 ⁇ x) SiO 2 where x is 0.2 and can be used in either in amorphous or crystalline form, preferably in amorphous form.
• the reaction is carried out in the presence of a promoter comprising 0.5-2%, preferably 1-2% transition metal oxide selected from the group consisting of Fe 2 O 3 , CuO, NiO and Co 3 O 4 , preferably Fe 2 O 3 .
• a promoter comprising 0.5-2%, preferably 1-2% transition metal oxide selected from the group consisting of Fe 2 O 3 , CuO, NiO and Co 3 O 4 , preferably Fe 2 O 3 .
• the nitric acid used is 10 to 70% nitric acid and the molar ratio of nitric acid to benzene used is 4:1 to ⁇ 1:4, preferably 1:2
• the nitration is carried out at a temperature preferably in the range of 120-200° C. and at a reactant weight hourly space velocity used is preferably in the range of 0.15 to 0.5.
• Inert gas is used as a carrier gas selected from the group consisting of nitrogen, helium and argon.
• the novelty of the present invention lies in the use of xMoO 3 :(1 ⁇ x) SiO 2 catalyst with or without promoter for vapour phase nitration of benzene in high yield and selectivity for nitrobenzene.
• MoO 3 /SiO 2 catalyst used in the present invention was prepared using ammonium molybdate (AR Grade, Loba make) as molybdenum source and ethyl silicate-40 (CAS Registry no. 18594-71-7, supplied by Chemplast) as silica source.
• ammonium molybdate AR Grade, Loba make
• ethyl silicate-40 CAS Registry no. 18594-71-7, supplied by Chemplast
• the catalyst was characterized using XRD, surface area using BET, chemical analysis by AAS and XRF. XRD showed amorphous nature of the catalyst and BET showed the surface area of 372 m 2 /g.
• the molar composition of the catalyst was 0.2 MoO 3 :0.8 SiO 2 .
• the catalyst was molded in the form of a pellet, which is granulated to ⁇ 10 to +20 mesh size for its use in nitration reaction.
• Fe 2 O 3 /MoO 3 /SiO 2 catalyst used in the present invention was prepared using ammonium molybdate (AR Grade, Loba make) as molybdenum source, ferric nitrate (SD fine) as iron source and ethyl silicate-40 (CAS registry no. 18594-71-7, supplied by Chemplast) as silica source. 5.65 g. of ferric nitrate was dissolved in 100 ml of isopropyl alcohol which was added to a solution 118.9 g of ethylsilicate-40 in 100 ml of isopropyl alcohol under constant stirring.
• ammonium molybdate AR Grade, Loba make
• ferric nitrate SD fine
• ethyl silicate-40 CAS registry no. 18594-71-7, supplied by Chemplast
• the product was condensed at 9° C. and collected in a receiver.
• the product was analyzed by gas chromatography. Results after 25 hours from beginning of reaction are shown below.
• Example 3 was repeated except increasing the Weight Hourly Space Velocity (WHSV) to 0.34. Reaction conditions were as follows.
• Example 3 was repeated except that benzene/HNO 3 ratio was changed.
• the reaction conditions were as follows.
• the XRD showed the presence of crystalline form MoO 3 and amorphous form of silica.
• the surface area of the catalyst was 215 m 2 /g.
• the catalyst was molded in the form of a pellet, which is granulated to ⁇ 10 to +20 mesh size for its use in nitration.
• the nitration reaction was carried out as mentioned in the Example 2.
• the reaction conditions were as follows.
• Example 3 was repeated except that temperature of the reaction was changed.
• the reaction conditions were as follows.
• Example 3 was repeated except that the catalyst with 0.7 mol % Fe 2 O 3 prepared as per example 2.
• the reaction conditions were as follows.

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• Chemical Kinetics & Catalysis (AREA)
• Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
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• 2003
  • 2003-05-30 EP EP03253422A patent/EP1386907B1/de not_active Expired - Lifetime
  • 2003-05-30 AT AT03253422T patent/ATE527234T1/de not_active IP Right Cessation
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